Outboard motor capable of being tilted up and trimmed in, and marine vessel therewith

ABSTRACT

An outboard motor includes a main body including a power source and a bracket to be attached to a stern of a hull. The main body is rotatable about a rotating shaft of the bracket such that an upper portion of the main body moves toward a front of a marine vessel and a lower portion of the main body moves toward a rear of the marine vessel, or such that the upper portion of the main body moves toward the rear of the marine vessel and the lower portion of the main body moves toward the front of the marine vessel. When the marine vessel is cruising, a distance from the rotating shaft to an upper end of the stern in a vertical direction of the marine vessel is equal to or longer than a distance from the rotating shaft to a propeller shaft in the vertical direction of the marine vessel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2022-036644 filed on Mar. 9, 2022. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an outboard motor capable of beingtilted up and trimmed in, and a marine vessel including the same.

2. Description of the Related Art

A relatively small marine vessel such as a planing boat has an outboardmotor as a propulsion device. As shown in FIG. 9A, an outboard motor 90includes an outboard motor main body 91 incorporating a power sourcetherein, and a bracket 93 provided with a tilt shaft 92. The bracket 93is attached to a stern 98 of a hull 94 of a marine vessel, and theoutboard motor main body 91 is attached to the bracket 93 so as torotate about the tilt shaft 92. Note that in FIGS. 9A to 9C, the leftside in the figures corresponds to a forward direction of the marinevessel, the right side in the figures corresponds to a rearwarddirection of the marine vessel, the upper side in the figurescorresponds to an upper direction of the marine vessel, and the lowerside in the figures corresponds to a lower direction of the marinevessel. The tilt shaft 92 extends in the crosswise direction of themarine vessel, and hence the outboard motor main body 91 rotates aboutthe tilt shaft 92 counterclockwise as viewed in the drawing (tilt-up)such that an upper portion 91 a moves forward and downward and a lowerportion 91 b moves rearward and upward (FIG. 9A), or rotates about thetilt shaft 92 clockwise as viewed in the drawing (trim-in) such that theupper portion 91 a moves rearward and downward and the lower portion 91b moves forward and upward (FIG. 9B) (see, for example, JapaneseLaid-open Patent Publication (Kokai) No. H01-317893).

Conventionally, a reciprocating engine 95, which is an internalcombustion engine, has been used as a power source for the outboardmotor 90. In an upper portion 91 a of the outboard motor main body 91,the reciprocating engine 95 is disposed such that a crankshaft liesalong the vertical direction and a cylinder head 96 lies behind acylinder block 97 (FIG. 9A). Thus, when the outboard motor main body 91is trimmed in to a great extent, at least a part of the cylinder head 96becomes positioned at a lower position than the cylinder block 97.Therefore, lubricating oil for a cylinder in the cylinder block 97 maybe burned in a fuel chamber without going back to a crankcase, and as aresult, the reciprocating engine 95 may blow white smoke. For thisreason, in the outboard motor 90 using the reciprocating engine 95, itis difficult for the outboard motor main body 91 to trim in to a greatextent.

Implementation of carbon-free mobile bodies as one of means forachieving recently-advocated SDGs (Sustainable Development Goals) hasbeen pursued, and as a power source for an automobile which is as anexample of mobile bodies, an internal combustion engine is beingincreasingly replaced with an electric motor.

As the power source of the outboard motor 90, it has also been studiedto replace an internal combustion engine with an electric motor as withthe automobile. If the power source of the outboard motor 90 is replacedwith an electric motor, the combustion of the lubricating oil describedabove will never happen, which will make it unnecessary to limit theamount of trim-in so as to prevent the white smoke. Trim-in has asignificant effect on posture control in the pitch direction while themarine vessel is cruising, and hence in the outboard motor 90 using anelectric motor as the power source, the outboard motor main body 91 isrequired to be trimmed in to a great extent from the standpoint ofincreasing the degree of freedom in posture control.

On the other hand, for the conventional outboard motor 90, the outboardmotor main body 91 is required to be tilted up to a great extent sincepriority is given to lifting the outboard motor main body 91 out ofwater when the marine vessel is anchored at a pier or the like for along period of time. Accordingly, in a conventional technique, byplacing the tilt shaft 92 in the vicinity of the upper portion 91 a ofthe outboard motor main body 91, even if the outboard motor main body 91is tilted up to a great extent, the amount of movement forward of theupper portion 91 a of the outboard motor main body 91 is kept small sothat the upper portion 91 a of the outboard motor main body 91 isprevented from interfering with the hull 94 (FIG. 9B).

However, if the tilt shaft 92 is placed in the vicinity of the upperportion 91 a of the outboard motor main body 91, the lower portion 91 bof the outboard motor main body 91 moves forward by a large amount whenthe outboard motor main body 91 is trimmed in, and therefore, even whenthe amount of trim-in is increased only a little, the lower portion 91 bof the outboard motor main body 91 may interfere with the hull 94 (FIG.9C). Thus, in the conventional outboard motor 90, it is difficult toincrease the amount (angle) of the trim-in of the outboard motor mainbody 91, and the outboard motor main body 91 is allowed to be trimmed inup to only about 4° about the tilt shaft 92. Namely, there is room forimprovement regarding the amount of trim-in that can be achieved.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention achieve a large trim-inof main bodies of outboard motors.

According to a preferred embodiment of the present invention, anoutboard motor includes a main body including a power source, a bracketto be attached to a stern of a hull of a marine vessel and including arotating shaft, and a propeller shaft to rotate a propeller at a lowerportion of the main body, wherein the main body is attached to thebracket and rotatable in a first direction and a second direction, inthe first direction, the main body is rotatable about the rotating shaftsuch that an upper portion of the main body moves toward a front of themarine vessel and the lower portion of a main body moves toward the rearof the marine vessel, in the second direction, the main body isrotatable about the rotating shaft such that the upper portion of themain body moves toward the rear of the marine vessel and the lowerportion of the main body moves toward the front of the marine vessel,and when the marine vessel is cruising, a first distance from therotating shaft to an upper end of the stern in a vertical direction ofthe marine vessel is equal to or longer than a second distance from therotating shaft to the propeller shaft in the vertical direction of themarine vessel.

According to another preferred embodiment of the present invention, anoutboard motor includes a main body including a power source, and abracket to be attached to a stern of a hull of a marine vessel andincluding a rotating shaft, wherein the main body is attached to thebracket and rotatable in a first direction and a second direction, inthe first direction, the main body is rotatable about the rotating shaftsuch that an upper portion of the main body moves toward a front of themarine vessel and a lower portion of the main body moves toward a rearof the marine vessel, in the second direction, the main body isrotatable about the rotating shaft such that the upper portion of themain body moves toward the rear of the marine vessel and the lowerportion of the main body moves toward the front of the marine vessel,and, in a vertical direction of the marine vessel, the rotating shaft iscloser to a lower end of the stern than to an upper end of the stern.

According to another preferred embodiment of the present invention, anoutboard motor includes a main body including a power source, and abracket to be attached to a stern of a hull of a marine vessel andincluding a rotating shaft, wherein the main body is attached to thebracket and rotatable in a first direction and a second direction, inthe first direction, the main body is rotatable about the rotating shaftsuch that an upper portion of the main body moves toward a front of themarine vessel and a lower portion of the main body moves toward a rearof the marine vessel, in the second direction, the main body isrotatable about the rotating shaft such that the upper portion of themain body moves toward the rear of the marine vessel and the lowerportion of the main body moves toward the front of the marine vessel,and, in a vertical direction of the marine vessel, the rotating shaft iscloser to a lower end of the main body than to an upper end of the mainbody.

According to the configurations described above, when the marine vesselis cruising, the first distance from the rotating shaft to the upper endof the stern in the vertical direction of the marine vessel is equal toor longer than the second distance from the rotating shaft to thepropeller shaft in the vertical direction of the marine vessel, therotating shaft is closer to the lower end of the stern than to the upperend of the stern in the vertical direction of the marine vessel, or therotating shaft is closer to the lower end of the main body than to theupper end of the main body in the vertical direction of the marinevessel. Namely, the rotating shaft of the main body of the outboardmotor is closer to the vessel bottom in the vertical direction of themarine vessel. Therefore, the amount of the forward movement of thelower portion of the main body when the outboard motor is rotated aboutthe rotating shaft such that the lower portion of the main body of theoutboard motor moves forward with respect to the marine vessel (trimmedin) is small, and thus even if the amount of trim-in is increased, thelower portion of the main body is able to be prevented from interferingwith the hull. As a result, the main body of the outboard motor is ableto be trimmed in to a large extent.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a marine vessel to which an outboard motoraccording to a first preferred embodiment of the present invention isapplied.

FIG. 2 is a side view useful in explaining the outline of aconfiguration of the outboard motor according to the first preferredembodiment of the present invention.

FIGS. 3A to 3C are views useful in explaining trim-in and tilt-up of anoutboard motor main body in the first preferred embodiment of thepresent invention.

FIGS. 4A to 4C are views useful in explaining a shift to a planing stateof a planing boat provided with an outboard motor including aconventional reciprocating engine.

FIGS. 5A to 5C are views useful in explaining a shift to a planing stateof a marine vessel provided with an outboard motor including an electricmotor according to the first preferred embodiment of the presentinvention.

FIG. 6 is a side view of a marine vessel to which an outboard motoraccording to a second preferred embodiment of the present invention isapplied.

FIG. 7 is a side view useful in explaining the outline of aconfiguration of the outboard motor according to the second preferredembodiment of the present invention.

FIGS. 8A to 8C are views useful in explaining trim-in and tilt-up of anoutboard motor main body in the second preferred embodiment of thepresent invention.

FIGS. 9A to 9C are views useful in explaining trim-in and tilt-up of aconventional outboard motor main body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, preferred embodiments of the present invention will bedescribed with reference to the drawings. A description will now beprovided of a first preferred embodiment of the present invention.

FIG. 1 is a side view of a marine vessel 10 to which an outboard motor13 according to the first preferred embodiment of the present inventionis applied. FIG. 2 is a side view useful in explaining the outline of aconfiguration of the outboard motor 13 according to the first preferredembodiment of the present invention.

The marine vessel 10 is, for example, a planing boat, and includes ahull 11 and at least one, for example, two outboard motors 13 as marinepropulsion devices to be attached to a stern 12 of the hull 11. A cabin14 also serving as a cockpit is provided in the hull 11. Although FIG. 1shows the marine vessel 10 in a planing state, the marine vessel 10 isnot limited to a planing boat, but may be, for example, a relativelysmall marine vessel of a displacement type.

Note that in the drawings to be referred to below, the left side in thefigures corresponds to a forward direction of the marine vessel 10, theright side in the figures corresponds to a rearward direction of themarine vessel 10, the upper side in the figures corresponds to an upperdirection of the marine vessel 10, and the lower side in the figurescorresponds to a lower direction of the marine vessel 10, a depthdirection in the figures corresponds to a right direction of the marinevessel 10, and a front direction in the figures corresponds to a leftdirection of the marine vessel 10.

The outboard motor 13 includes an outboard motor main body 16 includingan electric motor 15 as a power source therein, a bracket 18 providedwith a tilt shaft 17 (rotating shaft), and a lift mechanism 19 attachedto the stern 12 of the hull 11. In the outboard motor main body 16, theelectric motor 15 is located in an upper portion 16 a. The outboardmotor main body 16 further includes a propeller 20 and a propeller shaft21 to rotate the propeller 20 in a lower portion 16 b, and a drive shaft22 to transmit a driving force of the electric motor 15 to the propellershaft 21. The propeller 20 rotated by the driving force of the electricmotor 15 applies a propulsive force to the marine vessel 10. Thepropeller shaft 21 extends along the fore-and-aft of the marine vessel10, and the drive shaft 22 extends along the vertical direction of themarine vessel 10.

A steering mechanism (not illustrated) is provided in the outboard motor13, and by swinging the outboard motor 13 in the crosswise direction ofthe marine vessel 10 with respect to the hull 11, adjusts the directionin which a propulsive force generated by the outboard motor 13 acts withrespect to the crosswise direction.

The bracket 18 is attached to the stern 12 of the hull 1 via the liftmechanism 19, wherein the lift mechanism 19 moves the bracket 18 in thevertical direction of the marine vessel 10. The outboard motor main body16 is attached to the bracket 18. As a result, the lift mechanism 19moves the outboard motor main body 16 via the bracket 18 in the verticaldirection of the marine vessel 10.

The outboard motor main body 16 is attached to the bracket 18 rotatablyabout the tilt shaft 17. The tilt shaft 17 extends in the crosswisedirection of the marine vessel 10, and thus the outboard motor main body16 rotates about the tilt shaft 17 counterclockwise as viewed in thedrawing (first direction) such that the upper portion 16 a moves forwardand downward with respect to the marine vessel 10 and the lower portion16 b moves rearward and upward with respect to the marine vessel 10, orrotates about the tilt shaft 17 clockwise as viewed in the drawing(second direction) such that the upper portion 16 a moves rearward anddownward with respect to the marine vessel 10 and the lower portion 16 bmoves forward and upward with respect to the marine vessel 10. Note thatthe first direction will be referred to as “tilt-up”, and the seconddirection will be referred to as “trim-in”.

The bracket 18 includes a rotational mechanism, such as a power tilttrim (not illustrated), including a hydraulic actuator to tilt up theoutboard motor main body 16 and a hydraulic actuator to trim in theoutboard motor main body 16. The lift mechanism 19 includes a hydraulicactuator (not illustrated) to move the bracket 18 up and down.

While the marine vessel 10 is cruising, the lift mechanism 19 adjusts(changes) the position of the outboard motor main body 16 in thevertical direction via the bracket 18 so that the propeller 20 is ableto be entirely submerged under the water surface. At this time, thedistance L6 from the tilt shaft 17 to the lower end of the stern 12 inthe vertical direction is equal to or shorter than the distance L₁(first distance) from the tilt shaft 17 to the upper end of the stern 12in the vertical direction. Namely, the tilt shaft 17 is closer to thelower end of the stern 12 than to the upper end of the stern 12 in thevertical direction. Moreover, the distance L2 (second distance) from thetilt shaft 17 to the propeller shaft 21 in the vertical direction isequal to or shorter than the distance L₁. Further, the distance L4 fromthe tilt shaft 17 to the lower end of the outboard motor main body 16 inthe vertical direction is equal to or shorter than the distance L3 fromthe tilt shaft 17 to the upper end of the outboard motor main body 16 inthe vertical direction. Namely, the tilt shaft 17 is closer to the lowerend of the outboard motor main body 16 than to the upper end of theoutboard motor main body 16 in the vertical direction. In addition, thedistance L5 from the rear end of the stern 12 to the tilt shaft 17 withrespect to the fore-and-aft direction is greater than zero. Namely, thetilt shaft 17 is located more rearward than the rear end of the stern 12with respect to the fore-and-aft direction.

FIGS. 3A to 3C are views useful in explaining trim-in and tilt-up of theoutboard motor main body 16 in the first preferred embodiment.

As shown in FIG. 3A, while the marine vessel 10 is cruising, theoutboard motor main body 16 that has not been trimmed in or tilted up isheld by the bracket 18 such that the drive shaft 22 extends along thevertical direction. When a vessel operator or the like instructs to trimin the outboard motor main body 16, the power tilt trim of the bracket18 rotates the outboard motor main body 16 clockwise as viewed in thedrawing with respect to the tilt shaft 17 (FIG. 3B).

Here, as described above, in the vertical direction, the tilt shaft 17is closer to the lower end of the stern 12 than to the upper end of thestern 12, and the distance L2 from the tilt shaft 17 to the propellershaft 21 in the vertical direction is equal to or shorter than thedistance L₁ from the tilt shaft 17 to the upper end of the stern 12 inthe vertical direction. Namely, the tilt shaft 17 is closer to thevessel bottom, and in the outboard motor main body 16, the tilt shaft 17is closer to the lower end of the outboard motor main body 16 than tothe upper end of the outboard motor main body 16. Thus, the distancefrom the tilt shaft 17 to the lower end of the outboard motor main body16 is short, and thus the amount of the forward movement of the lowerportion 16 b of the outboard motor main body 16 when the outboard motormain body 16 is trimmed in about the tilt shaft 17 is small. As aresult, even if the amount of trim-in is increased, the interference ofthe lower portion 16 b with the stern 12 is prevented, and the outboardmotor main body 16 is able to be trimmed in to a large extent.

Moreover, in the present preferred embodiment, the tilt shaft 17 islocated more rearward than the rear end of the stern 12 with respect tothe fore-and-aft direction, as described above. In this arrangement, theoutboard motor main body 16 is spaced away from the stern 12, whichmakes the lower portion 16 b less likely to interfere with the stern 12when the outboard motor main body 16 is trimmed in about the tilt shaft17. Therefore, locating the tilt shaft 17 more rearward than the rearend of the stern 12 with respect to the fore-and-aft directioncontributes to achieving a large trim-in of the outboard motor main body16.

In this manner, in the present preferred embodiment, the large trim-inof the outboard motor main body 16 is achieved. Specifically, theposition of the tilt shaft 17 while the marine vessel 10 is cruising isset such that the maximum rotational angle θ₁ (maximum trim-in angle) isequal to or greater than about 20° (θ₁≥20°), more preferably equal to orgreater than about 30° (θ₁≥30°), wherein at the maximum rotational angleθ₁, the lower portion 16 b of the outboard motor main body 16 does notinterfere with the stern 12 of the hull 11 or the bracket 18 when theoutboard motor main body 16 is rotated clockwise as viewed in thedrawings with respect to the tilt shaft 17 from the state in which thedrive shaft 22 extends along the vertical direction (neutral state).

To anchor the marine vessel 10 at a pier for a long period of time forstorage, the outboard motor main body 16 is lifted out of water. In thiscase, the lift mechanism 19 raises the outboard motor main body 16 toits uppermost position via the bracket 18, and further, the power tilttrim of the bracket 18 tilts up the outboard motor main body 16 withrespect to the tilt shaft 17 (FIG. 3C). At this time, with the upwardmovement of the bracket 18, the tilt shaft 17 is positioned closer tothe upper side, and thus even if the amount of tilt-up is increased, theupper portion 16 a of the outboard motor main body 16 is prevented frominterfering with the stern 12 such that the large tilt-up of theoutboard motor main body 16 is achieved. As a result, the lower portion16 b of the outboard motor main body 16 is able to be relatively movedupward to a large extent, enabling the propeller 20 to be reliablylifted out of the water.

FIGS. 4A to 4C are views useful in explaining a shift to a planing stateof a planing boat provided with an outboard motor including aconventional reciprocating engine.

When a conventional planing boat 40 is cruising at low speed, lift forceis hardly generated at a vessel bottom, and thus as with a marine vesselof a displacement type, water draft has a predetermined depth. At thistime, an outboard motor 41 is hardly trimmed in, and the loadingdirection (acting direction) of a propulsive force f generated by apropeller 42 of the outboard motor 41 is parallel or substantiallyparallel to the water surface (FIG. 4A). Note that in FIGS. 4A to 4C,the loading direction of the propulsive force f is indicated bydot-dashed lines, and the water surface is indicated by a solid line.

When the vessel speed increases, a wave is generated due to cutwater ofa bow 43 of the planing boat 40, a hull 44 of the planing boat 40 israised by the wave crest, and a stern 45 of the planing boat 40 fallsinto a wave hollow, causing the planing boat 40 to be into a hump statein which the bow 43 is raised relatively (FIG. 4B). In the hump state,the resistance, wave-making resistance, and viscous resistance acting onthe hull 44 increase, making it difficult for the vessel speed toincrease, and therefore, no lift is generated at the vessel bottom,making it difficult for the planing boat 40 to go into the planingstate. To end the hump state, for example, a pitching moment (acounterclockwise moment as viewed in the drawings) to lower the bow 43should be generated about a center of gravity 46 of the hull 44 by thepropulsive force f.

However, the outboard motor 41 of the conventional planing boat 40 isable to be trimmed in up to only about 4° about a tilt shaft 47 asdescribed above, and the loading direction of the propulsive force fgenerated by the propeller 42 provided in a lower portion of theoutboard motor 41 is kept below the center of gravity 46. As a result, apitching moment 48 generated about the center of gravity 46 by thepropulsive force f is a moment clockwise as viewed in the drawings andacts on the hull 44 to raise the bow 43. Note that the pitching moment48 is indicated by white arrows in the drawings.

Accordingly, the conventional planing boat 40 is provided with a trimtab 49 as a posture control plate at the stern 45. The trim tab 49rotates at the stern 45 in the vertical direction of the planing boat40. In the conventional planing boat 40, lift force L is generated inthe vicinity of the bow 45 by the trim tab 49 being lowered. The liftforce L generates a pitching moment 50 (a moment counterclockwise asviewed in the drawing) to lower the bow 43 about the center of gravity46 (FIG. 4C). As a result, the bow is lowered, ending the hump state. Asa result, the resistance acting on the hull 44 is decreased to increasethe vessel speed, and the lift force generated at the vessel bottomenables the planing boat 40 to go into the planing state. Note that thepitching moment 50 is indicated by a hatched arrow in the drawing.

When the trim tab 49 is lowered, the resistance acting on the trim tab49 increases, and thus the reciprocating engine of the outboard motor 41is required to have high power output, leading to upsizing of thereciprocating engine and upsizing of the outboard motor 41. On the otherhand, in the marine vessel 10 provided with the outboard motor 13 usingthe electric motor 15 according to the present preferred embodiment, itis unnecessary to use a trim tab so as to end the hump state. A detaileddescription thereof will be given below.

FIGS. 5A to 5C are views useful in explaining a shift to the planingstate of a marine vessel 10 provided with the outboard motor 13including the electric motor 15 according to the first preferredembodiment.

As with the planing boat 40, when the marine vessel 10 is cruising atlow speed, lift force is hardly generated at the vessel bottom, and thuswater draft has a predetermined depth. At this time, the outboard motor13 is hardly trimmed in, and the loading direction (acting direction) ofa propulsive force F generated by the propeller 20 of the outboard motor13 is parallel or substantially parallel to the water surface (FIG. 5A).Note that in FIGS. 5A to 5C, the loading direction of the propulsiveforce F is indicated by dot-dashed lines, and the water surface isindicated by a solid line.

When the vessel speed increases, a wave is generated due to cutwater ofa bow 23 of the marine vessel 10, causing the marine vessel 10 to beinto a hump state in which the bow 23 is raised relatively (FIG. 5B). Asdescribed above, in the outboard motor 13, the position of the tiltshaft 17 while the marine vessel 10 is cruising is set such that themaximum rotational angle θ₁ is equal to or greater than about 20°(θ₁≥20°), and more preferably equal to or greater than about 30°(θ₁≥30°). As a result, the outboard motor main body 16 is able to betrimmed in to a large extent, and accordingly, the loading direction ofthe propulsive force F is turned upward to a large extent. Thus, theloading direction of the propulsive force F generated by the propeller20 is shifted above a center of gravity 24, and thus a pitching moment25 generated about the center of gravity 24 by the propulsive force F iscounterclockwise as viewed in the drawing and acts on the hull 11 tolower the bow 23 (FIG. 5C). Note that the pitching moment 25 isindicated by a white arrow in the drawing.

That is, in the present preferred embodiment, the outboard motor mainbody 16 is able to be trimmed in to a large extent, and the propulsiveforce F therefore generates the pitching moment 25 to lower the bow 23.As a result, it is possible to eliminate a necessity to use a trim tabfor the purpose of ending the hump state, and therefore eliminate thenecessity of a trim tab to be provided on the marine vessel 10.Moreover, the required output of the electric motor 15 is able to bereduced, and upsizing of the electric motor 15 is avoided.

A description will now be given of a second preferred embodiment of thepresent invention. The second preferred embodiment differs from thefirst preferred embodiment in that a marine vessel 60 is a hydrofoilboat, not a planing boat. The other configurations and operations arebasically the same as those of the first preferred embodiment describedabove, and thus corresponding configurations and operations will not bedescribed.

FIG. 6 is a side view of a marine vessel 60 to which an outboard motor13 according to the second preferred embodiment of the present inventionis applied. FIG. 7 is a side view useful in explaining the outline of aconfiguration of the outboard motor 13 according to the second preferredembodiment of the present invention.

The marine vessel 60 is a hydrofoil, and includes a hull 61 and at leastone, for example, two outboard motors 13 as marine propulsion devices tobe attached to a stern 62 of the hull 61. A cabin 63 also serving as acockpit is provided in the hull 61. FIG. 6 shows the marine vessel 60 ina foilborne cruising state, but the marine vessel 60 is not limited tothe hydrofoil, and may be, for example, a relatively small marine vesselof a displacement type equipped with hydrovanes.

The marine vessel 60 further includes hydrovanes 64. The hydrovanes 64may be moved to be accommodated in the hull 61. The number of hydrovanes64 is not limited. However, it is preferred that at least two hydrovanes64 are arranged side by side in the fore-and-aft direction of the marinevessel 60. When the speed of the marine vessel 60 increases, lift forcegenerated by the hydrovanes 64 increases, causing the hull 61 to leavethe water and causing the marine vessel 60 to go into the foilbornecruising state.

Note that in the drawings to be referred to below, the left side in thefigures corresponds to a forward direction of the marine vessel 60, theright side in the figures corresponds to a rearward direction of themarine vessel 60, the upper side in the figures corresponds to an upperdirection of the marine vessel 60, and the lower side in the figurescorresponds to a lower direction of the marine vessel 60, a depthdirection in the figures corresponds to a right direction of the marinevessel 60, and a front direction in the figures corresponds to a leftdirection of the marine vessel 60.

As with the first preferred embodiment, while the marine vessel 60 isfoilborne cruising, the lift mechanism 19 of the outboard motor 13adjusts the position of the outboard motor main body 16 in the verticaldirection via the bracket 18 so that the propeller 20 is entirelysubmerged under the water surface. The bottom of the marine vessel 60while foilborne cruising entirely floats over the water surface as shownin FIG. 6 , which requires the lift mechanism 19 to move the propeller20 downward to a lower position than the outboard motor 13 (the firstpreferred embodiment) provided in the marine vessel 10, which is aplaning boat.

Specifically, in order to move the propeller 20 downward, the liftmechanism 19 moves the outboard motor main body 16 downward to a lowerposition than the position of the outboard motor main body 16 while themarine vessel 10 is cruising (the first preferred embodiment). Thus, inthe second preferred embodiment, as distinct from the first preferredembodiment, the tilt shaft 17 of the bracket 18 is located at a lowerposition than the lower end of the stern 62, wherein the distance L6from the lower end of the stern 62 to the tilt shaft 17 in the verticaldirection is equal to or shorter than the distance L₁ from the upper endof the stern 62 to the tilt shaft 17. In other words, also in the secondpreferred embodiment, the tilt shaft 17 is closer to the lower end ofthe stern 62 than to the upper end of the stern 62 in the verticaldirection. Moreover, the distance L2 from the tilt shaft 17 to thepropeller shaft 21 in the vertical direction is equal to or shorter thanthe distance L₁. Specifically, the distance L₁ is twice or more as longas the distance L2. Note that in the first preferred embodiment and thesecond preferred embodiment, the outboard motor 13 has the samestructure, and thus as with the first preferred embodiment, the distanceL4 from the tilt shaft 17 to the lower end of the outboard motor mainbody 16 in the vertical direction is equal to or shorter than thedistance L3 from the tilt shaft 17 to the upper end of the outboardmotor main body 16 in the vertical direction. Namely, also in the secondpreferred embodiment, the tilt shaft 17 is positioned closer to thevessel bottom. Further, the distance L5 from the rear end of the stern62 to the tilt shaft 17 with respect to the fore-and-aft direction isgreater than zero, as with the first preferred embodiment.

FIGS. 8A to 8C are views useful in explaining trim-in and tilt-up of theoutboard motor main body 16 in the second preferred embodiment.

As shown in FIG. 8A, while the marine vessel 60 is foilborne cruising,the outboard motor main body 16 that has not been trimmed in or tiltedup is held by the bracket 18 such that the drive shaft 22 extends alongthe vertical direction. When a vessel operator or the like instructs totrim in the outboard motor main body 16, the power tilt trim of thebracket 18 rotates the outboard motor main body 16 clockwise as viewedin the drawing with respect to the tilt shaft 17 (FIG. 8B).

As described above, also in the second preferred embodiment, the tiltshaft 17 is closer to the vessel bottom, and the tilt shaft 17 is closerto the lower end of the outboard motor main body 16 than to the upperend of the outboard motor main body 16. Thus, the amount of the forwardmovement of the lower portion 16 b of the outboard motor main body 16when the outboard motor main body 16 is trimmed in about the tilt shaft17 is small. As a result, as with the first preferred embodiment, theoutboard motor main body 16 is able to be trimmed in to a large extent.Also in the second preferred embodiment, the position of the tilt shaft17 while the marine vessel 60 is foilborne cruising is set such that themaximum trim-in angle θ₁ is equal to or greater than about 20° (θ₁≥20°),more preferably equal to or greater than about 30° (θ₁≥30°). Note thatin the second preferred embodiment, the tilt shaft 17 is moved to alower position than in the first preferred embodiment, and thus in thesecond preferred embodiment, the lower portion 16 b of the outboardmotor main body 16 moves farther away from the stern 62 of the hull 61.In the second preferred embodiment, the lower portion 16 b of theoutboard motor main body 16 is farther away from the stern 62 than inthe first preferred embodiment, and thus the outboard motor main body 16is able to be trimmed in to a larger extent.

Accordingly, in the second preferred embodiment, the maximum trim-inangle θ₁ may be a larger value than the maximum trim-in angle θ₁ in thefirst preferred embodiment.

Note that as with the first preferred embodiment, to anchor the marinevessel 60 at a pier for a long period of time, the lift mechanism 19raises the outboard motor main body 16 to its uppermost position, andalso tilts up the outboard motor main body 16 with respect to the tiltshaft 17 (FIG. 8C).

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

For example, the outboard motor 13 may be equipped with any of thefollowing instead of an electric motor as a power source: an internalcombustion engine in which lubricating oil never returns to a crankcaseand burns even if the outboard motor main body 16 is trimmed in to alarge extent, such as a rotary engine, and a reciprocating engineoriented such that its cylinder head is never positioned below acylinder block when the outboard motor main body 16 is trimmed in.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. An outboard motor comprising: a main body including a power source; a bracket to be attached to a stern of a hull of a marine vessel and including a rotating shaft; and a propeller shaft to rotate a propeller at a lower portion of the main body; wherein the main body is attached to the bracket and rotatable in a first direction and a second direction; in the first direction, the main body is rotatable about the rotating shaft such that an upper portion of the main body moves toward a front of the marine vessel and the lower portion of the main body moves toward a rear of the marine vessel; in the second direction, the main body is rotatable about the rotating shaft such that the upper portion of the main body moves toward the rear of the marine vessel and the lower portion of the main body moves toward the front of the marine vessel; and when the marine vessel is cruising, a first distance from the rotating shaft to an upper end of the stern in a vertical direction of the marine vessel is equal to or longer than a second distance from the rotating shaft to the propeller shaft in the vertical direction of the marine vessel.
 2. The outboard motor according to claim 1, wherein, when the marine vessel is cruising, the first distance is twice or more as long as the second distance.
 3. The outboard motor according to claim 1, wherein, with respect to a fore-and-aft direction of the hull, the rotating shaft is more rearward than a rear end of the stern.
 4. The outboard motor according to claim 1, wherein, in the second direction, the main body rotates about the rotating shaft by a rotation angle of about 20° or more.
 5. The outboard motor according to claim 1, wherein, in the second direction, the main body rotates about the rotating shaft by a rotation angle of about 30° or more.
 6. The outboard motor according to claim 1, wherein a posture control plate that rotates with respect the vertical direction of the marine vessel is not provided at the stern of the hull.
 7. The outboard motor according to claim 1, further comprising a lift to move the main body in the vertical direction of the marine vessel.
 8. The outboard motor according to claim 7, wherein the lift is operable to change a position of the main body in the vertical direction of the marine vessel when the marine vessel is cruising.
 9. The outboard motor according to claim 7, wherein the marine vessel includes hydrovanes, and the lift is operable to move the main body downward to a lower side of the hull when the marine vessel is foilborne cruising.
 10. The outboard motor according to claim 7, wherein, to store the marine vessel, the lift raises the main body, and the main body rotates in the first direction.
 11. The outboard motor according to claim 1, wherein the power source includes an electric motor.
 12. A marine vessel comprising: an outboard motor including a main body including a power source; a bracket attached to a stern of a hull of the marine vessel and including a rotating shaft; and a propeller shaft to rotate a propeller at a lower portion of the main body; wherein the main body is attached to the bracket and rotatable in a first direction and a second direction; in the first direction, the main body is rotatable about the rotating shaft such that an upper portion of the main body moves toward a front of the marine vessel and a lower portion of the main body moves toward a rear of the marine vessel; in the second direction, the main body is rotatable about the rotating shaft such that the upper portion of the main body moves toward the rear of the marine vessel and the lower portion of the main body moves toward the front of the marine vessel; and when the marine vessel is cruising, a first distance from the rotating shaft to an upper end of the stern in a vertical direction of the marine vessel is equal to or longer than a second distance from the rotating shaft to the propeller shaft in the vertical direction of the marine vessel.
 13. An outboard motor comprising: a main body including a power source; and a bracket to be attached to a stern of a hull of a marine vessel and including a rotating shaft; wherein the main body is attached to the bracket and rotatable in a first direction and a second direction; in the first direction, the main body is rotatable about the rotating shaft such that an upper portion of the main body moves toward a front of the marine vessel and a lower portion of the main body moves toward a rear of the marine vessel; in the second direction, the main body is rotatable about the rotating shaft such that the upper portion of the main body moves toward the rear of the marine vessel and the lower portion of the main body moves toward the front of the marine vessel; and in a vertical direction of the marine vessel, the rotating shaft is closer to a lower end of the stern than to an upper end of the stern.
 14. An outboard motor comprising: a main body including a power source; and a bracket to be attached to a stern of a hull of a marine vessel and including a rotating shaft; wherein the main body is attached to the bracket and rotatable in a first direction and a second direction; in the first direction, the main body is rotatable about the rotating shaft such that an upper portion of the main body moves toward a front of the marine vessel and a lower portion of the main body moves toward a rear of the marine vessel; in the second direction, the main body is rotatable about the rotating shaft such that the upper portion of the main body moves toward the rear of the marine vessel and the lower portion of the main body moves toward the front of the marine vessel; and in a vertical direction of the marine vessel, the rotating shaft is closer to a lower end of the main body than to an upper end of the main body. 